Steve,Could this be just the run-to-run variation?I've always read that octane doesn't improve running unless you can take advantage of the extra detonation resistance with timing advance.I thought that the C14 doesn't have knock sensor(s) - or does it?If not, the engine shouldn't benefit from higher octane.

Steve,Could this be just the run-to-run variation?I've always read that octane doesn't improve running unless you can take advantage of the extra detonation resistance with timing advance.I thought that the C14 doesn't have knock sensor(s) - or does it?If not, the engine shouldn't benefit from higher octane.

No, not run to run deviation, though there are always deviations in runs. I could closely replicate the results with each octane value, but could never get the 89 to deliver what the 92 did, even at 3k rpm's. And the timing is optimized with the a/f ratio, so I feel we are seeing differences from fuel alone. It's marginal and you probably won't feel it, but it's there. Steve

Years ago Shell engineer told me the base stock, the point the product wasremoved from the cracking column, were different for the grades of gas. Therewould be small differants in the chemical makeup of the gases.

Steve,Could this be just the run-to-run variation?I've always read that octane doesn't improve running unless you can take advantage of the extra detonation resistance with timing advance.I thought that the C14 doesn't have knock sensor(s) - or does it?If not, the engine shouldn't benefit from higher octane.

No, not run to run deviation, though there are always deviations in runs. I could closely replicate the results with each octane value, but could never get the 89 to deliver what the 92 did, even at 3k rpm's. And the timing is optimized with the a/f ratio, so I feel we are seeing differences from fuel alone. It's marginal and you probably won't feel it, but it's there. Steve

Steve didn't you see something similar regarding Australian fuel versus USA fuel in a previous situation?

Years ago Shell engineer told me the base stock, the point the product wasremoved from the cracking column, were different for the grades of gas. Therewould be small differants in the chemical makeup of the gases.

What he told you is basically true, but the details are a little off. The refinery where I worked had two units to make the gasoline blend stock: a Low Pressure CCR for low octane stock, and a High Pressure CCR for high octane blend stock. Some people think it's the additives that make the difference in octane, but they start out with different products then add the other components.

Steve didn't you see something similar regarding Australian fuel versus USA fuel in a previous situation?

I couldn't pin anything down. I looked at the stoic values of pure gas and 10% ethanol fuel. there's a .5 difference, about 3-4% . A little more research indicated that the specipic gravity is about 4% heavier with pure gas. I adjusted my fuel maps to reflect that. Feedback has been positive.

I don't know the answer, but I do know; at higher RPM's the exact ignition point becomes more important.

Here's a wild guess;The HP increase may be because the 92 Octane is more resistant to ignition than the 89. Possibly the 89 ignites just a tiny bit {1/2 degree of crank rotation} sooner than the 92. So, maybe the {89} ignition,, occurs a tiny bit too soon. If so, it could minutely slow the piston, rather than applying an optimum downward force on the piston.

{also} The 92 is supposed to burn differently than the 89. {has a different Flame Propagation} [Think of the difference as a smooth burn, rather than a flash]. So maybe, that smoother burn is also pushing the piston more efficiently??

The main thing your missing is Kawasaki specifies the Premium for use in the C-14. We're not sure why that is; may be to produce peak power, may be to protect the engine from detonation. That said, we shouldn't disregard Kawasaki's specification.

"and"; Steve has now shown that you do get more power with the Premium,,,, So, why not use what they specify, and have more power.. {win, WIN} NOTE: In a normal day of riding, the .50 per gallon only costs a few extra bucks.. Most COGgers ride because we enjoy it. A few extra $$ to enjoy it more, is even better..

The main thing your missing is Kawasaki specifies the Premium for use in the C-14. We're not sure why that is; may be to produce peak power, may be to protect the engine from detonation. That said, we shouldn't disregard Kawasaki's specification.

"and"; Steve has now shown that you do get more power with the Premium,,,, So, why not use what they specify, and have more power.. {win, WIN} NOTE: In a normal day of riding, the .50 per gallon only costs a few extra bucks.. Most COGgers ride because we enjoy it. A few extra $$ to enjoy it more, is even better..

Ride safe, Ted

I don't mean to sound argumentative, but based on that graph, you're talking about less than 1hp. I look at that graph and say "unless there are other reasons to use more than 89 octane, this doesn't seem to convince me that I'm getting anything for the extra money to go from 89 octane to 92 octane.

(If there are mechanical reasons/longevity issues that justify 92+ octane, then by all means I'd continue using that)

I know that many use lower octane fuel and have no problems. They probably save $2.00 per fill up...

Kawasaki say's to use high octane in this engine. They also say, not doing so could possibly result in engine damage.. ie; It takes a lot of $2.00 savings to pay for a damaged engine.

"And" more power, {even only 1 HP} is still,,,,, more fun...

Make sense now?

Ted

Nope.

I've been riding a C14 for four years, have yet to see a reasonable explanation for why I need to use premium fuel other than "the manual says so." (although Steve's response above that it's smoother is a darn good reason for me to continue to use 92+).

It's not the extra $2 a fill-up, it's no real reason being given other than "that's what Kawasaki says." I had a Chrysler 300c that the manual said "use 87 octane." I got it custom dyno tuned and picked up 40 lb/ft of torque and almost 20hp on 92 octane. For me, that was reason to spend the extra money on premium gas.

My questions in this thread aren't critical, and I'm certainly not a cheap-a** when it comes to my bike, I'm just curious and interested in a real reason for the octane recommendation. I personally haven't noticed a difference when I've HAD to run 87 in the bike (traveling, no other options), and the dyno graph in this thread suggests that up to 9,000 rpm, no one else is going to, either.

The HP increase "smooth as silk" feeling may be because the 92 Octane is more resistant to ignition than the 89. Possibly the 89 ignites just a tiny bit {1/2 degree of crank rotation} sooner than the 92. So, maybe the {89} ignition,, occurs a tiny bit too soon. If so, it could minutely slow the piston, rather than applying an optimum downward force on the piston.

{also} The 92 is supposed to burn differently than the 89. {has a different Flame Propagation} [Think of the difference as a smooth burn, rather than a flash]. So maybe, that smoother burn is also pushing the piston more efficiently {and making the bike feel smoother}??

Ride safe, Ted

PS: I am not being a s___t A--. You have a good question. Just trying to reason-out what is happening..

I've heard that people who race (like in dragsters) use regular unleaded because they get faster times than when using premium. I've been using Costcos third tier rated regular for this last year and have never had a ping. Even starting out in second gear a couple of times on accident. (on my c14). Still get about fifty mpg average at least. I think the variable timing is making this possible.

The main thing your missing is Kawasaki specifies the Premium for use in the C-14. We're not sure why that is; may be to produce peak power, may be to protect the engine from detonation. That said, we shouldn't disregard Kawasaki's specification.

"and"; Steve has now shown that you do get more power with the Premium,,,, So, why not use what they specify, and have more power.. {win, WIN} NOTE: In a normal day of riding, the .50 per gallon only costs a few extra bucks.. Most COGgers ride because we enjoy it. A few extra $$ to enjoy it more, is even better..

Ride safe, Ted

Premium or 90 octane? I suppose that you are correct on this Ted, as mid grade is usually 89, so then were forced to go to premium which is 91 or even 93, at least here in Fl.